[TowerTalk] 2nd thrust bearing inside tower - you opinions??

KC4HW jimjohnson at alaweb.com
Mon Feb 26 19:26:19 EST 2007

As the debate goes on....  I really don't have any creditable input for the debate, but had 
decided several months ago to design a holding fixture that would fit inside a Rohn 45 tower 
some where between the rotator and the thrust bearing. 

Wanted it to provide for two purposes. 

1.  to hold the mast/antennas when changing the rotor.

2.  include two attachment points for pulley(s) at the bottom of the fixture.  So that a clamp 
could be fastened temporarily to the mast near the top of the rotator and the mast and 
antenna(s) could be raised to a distance to permit the rotator to be removed.  

Depending on pulleys, this would provide a 4 to 1 or 8 to 1 mechanical advantage.  I am 
going to have a 40-2CD, 204BA and a chrome moly 2" x 1/4" x 21' mast--approximately 215 

Based on the initial design and the machine shop input here is what we can up with.  This 
will fit into a R45 section and fasten on the sides with U-clamps.  Needs some paint, but 
here are some pics of the finished fixture...


Additionally, I thought that if I had to remove the rotator for repair and if it was going to be an 
extended period, that I would place a steel plate in place of the rotator and allow the mast 
and antennas to rest on the plate and not on the holding bolts in the fixture or the thrust 

It was totally manufactured from scrap (BTW there is no such thing in a welding shop.. hi)...  
He made this and a couple for accessory plates for the rotator and thrust bearing to fix a r45 
section and aligned the center holes.  

For what it is worth...  

http://www.AlabamaQSOParty.org (June 2nd and 3rd, 2007)

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